Rework and supplement admin Volumes

* Add volume snapshots
* Introduce tabs for Volumes, Types, and Snapshots
* Modify tests for new structure
* Add test for snapshot deletion
View snapshot details from admin
Add project name to snapshot detail
Remove test for admin snapshot details due to unmockable nested api call
US95: As admin, I want to upload volume as image

* Upload action added to Volumes table, in dropdown on each row
Merge branch 'master' into batch-5-clean

Conflicts:
	openstack_dashboard/dashboards/admin/volumes/tests.py
	openstack_dashboard/dashboards/admin/volumes/views.py
Update volume tests and tabs for latest codebase changes
Small fix for tenant_list call in volumes tabs
Restrict upload-image action to unattached volumes
Merge branch 'batch-5-clean' into dev

Conflicts:
	openstack_dashboard/api/cinder.py
	openstack_dashboard/dashboards/admin/volumes/tables.py
	openstack_dashboard/dashboards/admin/volumes/urls.py
	openstack_dashboard/dashboards/admin/volumes/views.py